JERUSALEM (AP) — Israelis ushered in the holiest day of the Jewish calendar at sundown Friday as nearly the entire country ground to a halt for Yom Kippur, Judaism’s day of atonement, observed with a 25-hour fast and long prayers.

Jews traditionally spend the solemn day fasting and asking God for forgiveness at intense prayer services in synagogues. It caps a 10-day period of soul-searching that began with Rosh Hashana, the Jewish New Year holiday.

In Israel, the country virtually shuts down for Yom Kippur. Businesses, restaurants and offices close, and television and radio stations go silent. Airports close and buses and trains stop running. Highways and roads become eerily quiet, devoid of vehicles.

Yom Kippur is unique in Israel because it touches almost the entire country. A high portion of the secular population observes the fast — and even those who don’t fast tend to refrain from eating in public, and quietly watch movies or rest at home.

Many secular, mostly younger, Israelis ride bicycles and skateboards through the empty roads in some areas.

The Israeli military closed crossings with the West Bank for the holiday, which starts on Friday evening, citing “security assessments.”

Israel has imposed West Bank closures during most Jewish holidays in recent years due to concerns that Palestinian militants could take advantage of the occasion to carry out attacks inside Israel.

This year, the holiday marks 40 years since the 1973 Arab-Israel War, which Israelis call the Yom Kippur War because of the surprise attack launched by the Egyptian and Syrian armies against Israel that year.

The war is etched deep in Israel’s collective psyche due to the heavy losses sustained in the fighting and because of the country’s lack of preparedness. For Israelis, it is one of the most traumatic events in their history. Personal accounts of Israelis who participated in that war or who were scarred by its occurrence filled newspapers and talk shows ahead of this year’s holiday.

The holiday also comes amid the crisis over reports of chemical weapons use in neighboring Syria’s civil war.

Israel is warily watching as the international community decides how to respond to the use of the deadly munitions that allegedly killed hundreds near Damascus last month. Washington and its allies say the Syrian regime of President Bashar Assad fired warheads in the Aug. 21 attack with a nerve agent, most likely sarin.

Israel has said it doesn’t want to get involved in the fighting but has also warned it will not tolerate chemical weapons reaching violent groups sworn to its destruction, such as the Iranian backed Lebanese Hezbollah group or the al-Qaida affiliates fighting in Syria against the regime.

For devout Jews, Yom Kippur is the most solemn day on the calendar where according to tradition, God weighs people’s deeds and decides their fate for the next year.

On Thursday night, thousands of Jews attended pre-Yom Kippur prayers in Jerusalem at the Western Wall, a remnant of the biblical Jewish Temple compound and the holiest site where Jews can pray.

Those observing the holiday refrain from food and drink and adhere to prohibitions that ban work, using electricity or operating any kind of machinery. The ban on drinking is especially tough in Israel where meteorologists have predicted the holiday this year will be the hottest in decades. Medics are on alert around the country to deal with emergencies.